Local Area Networks (LANs) are used as the basis for communications between computers and other network elements in business, campus, and residential environments. The predominant protocol for LAN communications is Ethernet, which can be realized in a number of formats including 10BASE-TX, 100BASE-TX, 1000BASE-FX, and Gigabit Ethernet. The Ethernet physical and data link layer (Layer 1 and Layer 2) specifications define how computers can communicate information over the various types of physical connections which can include twisted wire pairs, coaxial cables, and fiber optic cables.
Wide Area Networks (WANs) are the means in which data is transmitted between locations, and can include the transmission of data between buildings or campuses. The data is typically transported over telecommunications circuits which are provided by Interexchange Carriers (IXCs, also known as long distance providers), Competitive Access Providers (CAPs), Incumbent Local Exchange Carriers (ILECs), and Competitive Local Exchange Carriers (CLECs). Although these circuits can exist in a number of formats and data rates, a commonly used format is the Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH) standards developed for the transport of data over fiber optic networks. The SONET/SDH standards support the transport of data at data rates varying from 50 Mb/s (Synchronous Transfer Signal-1 (STS-1)) to 10 Gb/s (STS-192).
Present equipment provides for the ability to map Ethernet to SONET/SDH by providing Packet-Over-SONET (POS)/SDH Level 2 interfaces. These interfaces provide connectivity to Ethernet networks on one side of the interface, and connectivity to SONET/SDH networks on the other side of the interface. Present solutions provide the ability to map Ethernet into fixed bandwidth SONET/SDH transport pipes. This allows a customer to reserve a particular amount of WAN transport bandwidth in a fiber optic connection and to map the data onto that connection.
The shortcoming of the present solution is that the data is mapped into a single bandwidth connection, forcing the customer to reserve a particular amount of bandwidth in the fiber optic connection. If the bandwidth later proves to be inadequate due to growth, the customer will be required to replace the POS/SDH equipment and/or to lease additional bandwidth. If the customer purchases bandwidth and POS/SDH equipment having a bandwidth greatly in excess of what is presently needed, the costs may be excessively high. For the foregoing reasons, there is a need for a method and apparatus for flexibly mapping packet based LAN data onto a WAN connection.